Looks fine!One thing you can simplify: you can replace the lines 33 to 38 by

POL_Call POL_GoG_install

It will take care of any adjustments needed to run GOG installers (above .pdf extension association, but also install gdiplus, needed for installers v2), and then run the $POL_GoG_location installer, all by itself.Beside simplification, the other benefit is that if their installers need some more adjustments, it only needs to be done once, in POL_GoG_install function...

After that small change, feel free to submit the script for inclusion to the official repository ("Supported softwares" link, then "New installer"; And after script sending "Request signing" for validation).Ah, I may also need to 22x22 PNG version of the game icon for display in script lists (both in PlayOnLinux and in the website).